[llvm-readobj] Accept -S as an alias for --sections

In GNU readelf, the short option for --sections is upper-case -S.

Note that GNU uses lower-case -s to mean --symbols, while LLVM
uses -s to mean --sections and -t to mean --symbols (-t has yet a
different meaning in GNU). So command-line uses with -S can now
be compatible, but uses with -s or -t are still incompatible.

Patch by Roland McGrath

Differential Revision: https://reviews.llvm.org/D33872

llvm-svn: 308392
diff --git a/llvm/tools/llvm-readobj/llvm-readobj.cpp b/llvm/tools/llvm-readobj/llvm-readobj.cpp
index 51991a3..0a76368 100644
--- a/llvm/tools/llvm-readobj/llvm-readobj.cpp
+++ b/llvm/tools/llvm-readobj/llvm-readobj.cpp
@@ -57,12 +57,16 @@
     cl::desc("Alias for --file-headers"),
     cl::aliasopt(FileHeaders));
 
-  // -sections, -s
+  // -sections, -s, -S
+  // Note: In GNU readelf, -s means --symbols!
   cl::opt<bool> Sections("sections",
     cl::desc("Display all sections."));
   cl::alias SectionsShort("s",
     cl::desc("Alias for --sections"),
     cl::aliasopt(Sections));
+  cl::alias SectionsShortUpper("S",
+    cl::desc("Alias for --sections"),
+    cl::aliasopt(Sections));
 
   // -section-relocations, -sr
   cl::opt<bool> SectionRelocations("section-relocations",